1. Field of the Invention
The present invention relates generally to the field of measuring and testing and, more specifically, to a diametral clamp element used in devices for determining axial loads on a generally cylindrical member.
2. Description of the Related Art
In many areas it is necessary to measure diametral changes in generally cylindrical members to determine axial load.
One known device for determining axial loads is described in U.S. Pat. No. 4,911,004, issued to Leon. As shown in FIG. 2 herein, the Leon device is a clamping mechanism in which a pair of clamp elements A and B are positioned in contact with a cylindrical member (shown in phantom lines) by an adjustment screw which carries clamp element A. The clamp body, which is in the form of a C-clamp, is coupled to a strain gauge which is further coupled through an A/D converter to a computer. The device thus enables a determination of axial loading on the cylindrical member from signals generated by the strain gauge.
Each of the clamping members A and B is described as a V-block with a constant included V-angle of about 150.degree.. The angle is designed to permit the transmission of a percentage of the diametral change to the measuring device through the clamp body. The V-shaped elements provide torsional stability for the clamp assembly as well as transmitting a portion of the diametral change to the clamp assembly.
Clamp element A is illustrated in greater detail in FIG. 3, wherein it can be seen that, while the V-shaped surface of the clamp element is useful in centering the clamp element A relative to the cylindrical member, the cylindrical member is actually contacted at two different contact points, C and D, located on opposite sides of the line of symmetry of the cylindrical member. By having the point (or points) of contact away from the centers of both the clamping element and the cylindrical member, deformation or elasticity in the V-clamp surface can significantly contribute to measurement error.
Thus, a need exists for an improved clamping element which is capable of transmitting 100% of the diametral change to a measuring device while at the same time providing torsional stability.